This invention relates generally to transporting and unloading containers, and more particularly to an apparatus and method for transporting particulate lading in a container from one site and then unloading the particulate lading from the container at a second site.
Particulate ladings, such as polycarbonate or thermoplastic materials, synthetic resins, for example, are normally loaded within boxes, bags, containers or the like at a site where the polycarbonate plastic material is manufactured, and then transported by wheeled vehicle to a site where the plastic material is unloaded from the container into a storage facility for subsequent use in the manufacture of various plastic end products. It is highly desirable that such plastic materials or ladings, such as polyethylene pellets, not be contaminated by foreign matter or the like as even small amounts of foreign matter or contamination affect the quality of the subsequent manufactured products. Heretofore, plastic liners or bags such as vinyl or polyethylene liners have been used within containers to protect the lading from contamination. The plastic liners are normally sealed at the initial loading site and the lading is maintained in sealed relation within the plastic liner until unloaded at the unloading site, thereby insuring that the plastic lading will not be contaminated. Normally, the plastic lading is unloaded at the unloading site from the container by a suction or vacuum line extending within the container and then is conveyed pneumatically to a storage facility, such as bins, silos, or the like, until needed for the production of plastic end products. Pressurized air is sometimes used to push or aid in pushing the particulate plastic material from a container into a pneumatic discharge line for pneumatically conveying the plastic material into the storage facility.
U.S. Pat. No. 4,247,228 dated Jan. 27, 1981 shows a dump tractor or trailer having a container secured thereon for transporting sand and a pneumatic conveyor is secured to an end of the container for unloading the sand. Upon unloading, the container is tilted for discharge into a pneumatic conveyor and air is drawn in the container through hatches as the sand is dumped from an opening at the rear of the container. The container or truck bed is not removable and cannot be loaded at a site separate from the dump truck or trailer.
U.S. Pat. No. 4,449,861 dated May 22, 1984 shows a system for transporting plastic articles utilizing a tiltable van which is supplied with compressed air for forcing the plastic articles from an outlet at the end of the van for discharge into a pneumatic conveyor. The tiltable van is fixed to the vehicle and cannot be unloaded at a site separate from the dump truck or trailer.
Prior art unloading systems heretofore have utilized trailers with container support frames pivotally mounted for tilting at an end of the trailer for unloading particulate lading from an end of the container by gravity. However, such prior art trailers have not utilized pneumatic discharge apparatus mounted on the trailer forwardly of the rear wheels thereof and rearwardly of the rear end of the container for effective unloading of the container by gravity upon tilting of the container.